FD, it was a long time ago now but we were in a Q400 (no idea what version of TCAS we had) and somewhere at or below FL250 so not RVSM but maintaining level. The Airbus was climbing well to 1000' below us and we had the RA as they approached their level.
We reported the RA and ATC asked them if they'd had one as well but they said they'd only had a TA.